Lightning presents a frequent and inevitable risk to commercial and military aircraft as well as other vehicles and equipments. Electronic or electrical equipment in an aircraft must be tested to verify whether the equipment can handle the effects of a lightning surge. The equipment (hereinafter, referred to as “equipment under test (EUT)”) in the aircraft may be analyzed to classify its failure condition and to assign the appropriate certification level. Once lightning certification levels are determined for the EUTs, then the appropriate test levels may be assigned.
Various test standards have been developed by agencies. As a non-limiting example, the radio technical commission for aeronautics (RTCA) has established commercial test standards such as RTCA/DO-160 that is used in the military and aerospace industries. In particular, the RTCA/DO-160 verifies whether an EUT can operate as specified during and/or after various lightning induced test transient signals are injected into connector pins, interconnecting cables, and power leads of the EUT, using pin injection and/or cable bundle tests. The pin injection test is normally used to show damage tolerance of the EUT, while the cable bundle tests are used to show upset tolerance thereof.
For the capability of the EUT to withstand lightning transients to be verified, the test transient signals being injected into the EUT must be generated to represent actual induced effects of lightning. Thus, the test standards define specific waveforms and levels of the test transient signals depending on test levels and/or purposes.
Existing lightning tests on the EUT in accordance with the test standards (e.g., RTCA/DO-160) have been performed based on a single pin injection method in which each individual pin of the EUT is tested one at a time, which results in extensive test time and cost. The single pin test is also not reflective of an actual lightning strike that is not constrained to single pin operation. Although some test standards (e.g., RTCA/DO-160) describe a multiple pin injection test, it may be applicable only for loads with relatively high impedances or require using several synchronized signal generators which is considered to be difficult, so as to provide transients signals to the multiple test pins of the EUT simultaneously.
Thus, there is a need of a novel test method or system for testing an EUT, which reduces the test time and therefore reduces cost.